Patent GB-275343-A (GB)
Title: Improvements in or relating to telephone or like systems
IPC: H04Q3/42
Filed: 1926-05-07
Abstract: 275,343. Automatic Telephone Manufacturing Co., Ltd., and Tench, F. May 7, 1926. Automatic exchange systems. - A register controller which transmits only the office code comprises a singlemotion office register SS which responds to two digits, being set two steps per impulse by the first and one step per impulse by the second. The register has two sets of three marking wipers such as 73 the set to be used depending on the value of the first digit. Other features of the register controller relating to the transmission of impulses are claimed in Specification 285,279. The subscriber's dial may be locked while the code is being sent out e.g. by interrupting the line current, or he may be instructed to dial an unnecessary digit, or, as in the system described, to wait for the re-connection of dial tone. Selecting and setting register controller. When the calling line-switch finds the trunk circuit shown, relays A, B, start the switch DS which hunts for an idle register controller whereupon relay K substitutes dialling tone DT for busy tone BT which has so far been connected to the calling line. In the register-controller relays H, S, pull up. The digits are repeated over 32, C to the back-stroke magnet RM of the register. At the beginning of each impulse of the first digit, relay F pulls up its light armature 50 and, when the magnet RM removes the short circuit from the lower winding, all its armatures, releasing magnet RM which moves the wipers one step, relay F remaining energized over RM, C, 52. At the end of the impulse, relay A completes a circuit over 33, 46, 52 C energizing magnet RM and short-circuiting relay F which releases magnet RM causing a second step. At the end of this digit, relay Z which was energized by relay C and caused relay X to pull up its light armature 37, is released allowing relay X to pull up all its armatures. In the interval between the relapse of relays C, Z a circuit is made if necessary over 71, 48, 45<1> for the wiper changing relay L. Since relay F is now disconnected the second digit moves the register in the usual way. Relay C at the beginning of the digit causes relay Y to pull up its armature 41 and at the end allows it to pull up fully, connecting the out-impulsing circuit to the wires 32, 33, initiating impulse transmission by grounding 88, and energizes relay Z. Before relay Z (which is rather slow) has time to pull up a circuit 44, 39 is made for relay D which pulls up its armature 20 and then, on the energization of relay Z, its other armatures, switching the wires 32, 33 to the outgoing trunk, and cutting off the dial tone. Transmitting route code. Assuming the interrupter I to be in the break position when ground is connected to 88, relay R pulls up and locks up relay S. At the next make, relay R is shunted out and magnet DM, which is of the back stroke drive type, pulls up but does not send an impulse as the loop springs 62 are shunted at 70 by relay S which holds on to the interrupter. At the next break, relay S falls before relay R can pull up and the wipers advance to their first position. Each subsequent energization of magnet DM sends an impulse. If the interrupter is in the make position when relay Y pulls up, relay R does not pull up as its circuit is opened by relay S which is released as soon as the sending switch takes its first step. The digit is terminated when wiper 82 finding ground over IDF, 92 (or 99), 75, 79, energizes relay Q which disconnects the interrupter and energizes relay S which energizes relay R, and cuts off relay Q. When relay Q falls back the sending switch takes one step without sending an impulse as it did before the first digit and then begins to send out the second digit which is terminated as before when wiper 82 finds ground, this time over 76, 78. The third digit is sent in a similar way, but when wiper S1 reaches its final terminal, relay T pulls up in two steps, and replaces wiper 82 by wiper 83 which terminates the digit on finding battery over 95, 77, energizing relay R over 88. Had fewer than three digits been necessary the register would have energized relay M or N to cause relay R to be energized after two digits or one only. Switch-over in trunk circuit.; transmitting subscriber digits. Relay R completes a circuit 66, 64, 34, 21 for relay E which extends the calling loop to the selectors, re-connects dialling tone DT, and releases relay K. Relay A however is held over 18, 24 and holds up relay D until the first impulse of the next digit whereupon both relays fall back permanently, releasing relay B which removes dialling tone. Release of register controller. On the relapse of relay K, relay H releases relays X, Y, Land relay Z releases relays T, R. The register and the sending s'witch go home over wipers 71, 81. Premature dialling. If the subscriber dials during the route code, relay K is unlocked at 5 and releases the register controller and busy tone is connected up at 17. Provisional Specification. The register controller differs from that just described in the following respects (1) The relay F is omitted, the magnet RM being connected to the front contact of relay A by relay C (2) Relay Z is not energized by relay C and accordingly relay Z pulls up immediately on the relapse of relay C and the circuit for relay L is made over a back instead of a front contact of relay Z (3) The sending switch does not take an idle step before each digit but an equivalent effect is produced with the aid of a two-step relay which is connected to the interrupter and does not connect up the sending switch magnet until the first break after the transmission of a digit is initiated. The register may be made to take (say) four steps per impulse with the aid of a local circuit.